Abstract

Introduction: Since more than 50 years, various surgical procedures have been described for congenital Brown’s syndrome. However most showed low success rates and some even severe side effects.
The aim of this retrospective study was to evaluate the results of superior oblique posterior tenectomy. This technique was introduced in 1996 by Mühlendyck. Since this first description no other results have been published by others.
Patients and methods: 21 patients with congenital Brown’s syndrome (aged 2 to 29 years) were operated between 2001 and 2006, in the Department of Ophthalmology, Ludwig-Maximilians-University Munich. In all patients, intraoperative forced ductions showed severe passive restriction of elevation in adduction and superior oblique posterior tenectomy was performed as a primary procedure. The squint angle (vertical and horizontal deviation in primary position, lateral gaze, up/down gaze), active elevation in adduction, abnormal head posture at distance fixation, binocular vision (in primary position and anomalous head posture) were assessed in each case.
All the measurements were performed 1 day before, 1 month and 3 months after surgery. Eight patients were examined 6-24 months after primary procedure.
Results: Intraoperatively, a tight or very tight posterior part of the superior oblique tendon was found in 87 % of operated eyes.
At the end of the operation, passive motility in adduction became free (14 eyes) /almost free (7 eyes) on the majority of operated patients (totally 23 eyes).
Inspite of free passive motility, the active monocular elevation in adduction was only slightly improved by 0.5 mm to 5 mm (mean 2.25 mm), like hypotropia in primary position, which was improved by 1 to 12 deg (mean 4 deg).
Better results regarding hypotropia in primary position were noted when the preoperative vertical deviation in primary position was more than 10 deg. However in cases with preoperative hypotropia less than 10 deg, a better fusion was obtained.
Preoperatively, 17 patients showed an abnormal head posture. Postoperatively, 12 of them totally gave up their posture and 5 improved partially.
Of 8 cases with a long-term follow-up, 5 showed unchanged measurements of vertical deviation in primary position, monocular elevation in adduction and head posture. 3 patients with a long-term follow-up had further surgery and an improvement of vertical deviation in straight gaze and active elevation in adduction.
Conclusion: The use of superior oblique posterior tenectomy significantly improves abnormal head posture and also improves alignment and ocular rotations in patients with congenital Brown’s syndrome. We did not see any serious side effect like consecutive superior oblique muscle underaction (as in superior oblique tenotomy or recession) and no foreign body extrusion (as in silicone superior oblique tendon expander). So the superior oblique posterior tenectomy is a safe and effective procedure with regard to the head posture.
The fact that the passive motility had dramatic improved postoperatively, but the active elevation in adduction improved only slightly, suggests a paretic/ dysinnervational component to the superior oblique in some patients.
From this point of view, a therapeutic algorithm depending on intraoperative/ radiological findings in congenital Brown’s syndrome is proposed.